Petra et al,

John wrote, �gIf you can hear 5 meters of rock move less than a micron smoothly over many hours from many km away, I'm very impressed.�h

This is a polite way of saying that hearing this sound would be impossible, especially hearing it as a loud sound. I agree. The only choices of explanation are electrophonic transduction or maybe sound-signal amplification (the weak vibrations are themselves the source being transduced, not EM radiation).

�gJust to be straightforward, the electrical discharge from a square meter of rock grinding 1 micron in 6 hours is so small one couldn't measure it from 3 ft away, let alone hear it from its conversion to sound waves through 10 miles of rock.�h

Apparently, John is talking about the actual movement involved in this �grate and state�h theory. But the movement resulting in electrical discharge has no necessary connection to this theory, and presumably occurs over hundreds or thousands of meters. Moreover this �gmovement�h is not an actual displacement of rock from one location to another, but is movement within the rock itself: simply, it is the alternate increase and decrease of strain and stress. As I mentioned on the other thread, both professional physicists and amateurs have measured huge increases in ULF EM radiation.

Petra wrote, �gHere's a question I'm sure John could secure the answer to from an associate. In Bruce Bolts book "Earthquakes" he said that when rocks are broken in the lab they emit an electrical discharge. So at what frequency is the sound that comes from that?�h

The answer is that ULF radiation results. Another possible cause of ULF surges is that as internal movements (stress rate changes) occur along a fault, the electrical conductivity of the ground changes. For the rock-breaking idea,
�gOn the possible origin, propagation and detectability of ELECTROMAGNETIC PRECURSORS OF EARTHQUAKES
by E. R. Mognaschi (upd Apr 2003)�h
Mognashci is doing laboratory work in Italy on breaking rocks to measure piezo-electric results. He wrote me, graciously giving advice and suggestions.
(Recommended ULF website: Radio waves below 22 kHz
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=9691).

�gNow imagine that you are a�c rock, way down under the ground�c and a fracture occurs, but it isn't enough to push the fault to an earthquake, what kind of sound would you make?�h

That would depend on the length of the fracture, but most likely the frequency would be very low. Low frequency sound also results from the earthquake itself too. (We heard that often in 1995 quake and aftershocks). For a comparison, a very low musical note has a length of about 2 meters.

http://www.phy.mtu.edu/~suits/notefreqs.html
Note Frequency (Hz) Wavelength (cm)
Lower end
C0 16.35 2100.
C#0/Db0 17.32 1990.
D0 18.35 1870.
D#0/Eb0 19.45 1770.
E0 20.60 1670.
F0 21.83 1580.
F#0/Gb0 23.12 1490.
G0 24.50 1400.
G#0/Ab0 25.96 1320.
A0 27.50 1250.
A#0/Bb0 29.14 1180.
B0 30.87 1110.
C1 32.70 1050.

�gYou already know that electricity is at work there, so it just magnified by a 1000 times or so from the laboratory test.�h

Guesswork on your part, but acceptable. Problem is, John is talking about stuff that would result from a �grate and state�h scenario, which neither you or I know much about. If electrical discharge is not a part of that scenario, your point can be rejected by John, since for him �grate and state�h is under discussion here.

�gCan someone hear that?�h
No.

�gMaybe not in the normal sense one thinks of hearing, but maybe they can hear the vibration it sends out that seems like a sound to the person who is hearing it? �g

If an EM vibration seems like sound, then electrophonic transduction has taken place. That is what it is. Your wording will cause John to wonder again if you are not talking about some new kind of vibration unexplainable by science.

Regarding the characteristics of the sound you hear:
A: This would be a sort of rhythmic roar?

P: No. Just hugely loud, constant, no dips, no fades, just coming at you.

In that case, it might be easy to simulate the sound using the NCH Tone Generator I mentioned.

A: Do you ever hear sounds that are simply of one frequency, either a single musical pitch, or a simple rhythmic clicking sound?

P: Yes,I hear many ear tones that are a single pitch, but I've never heard a clicking sound.

Again, you could use the Tone Generator to identify the range of specific tones you normally hear, or any tones that have special meanings (which frequencies you associate with which faults, etc). That way, you could be very specific in communicating what you are hearing and what your interpretations are.

�gSometimes there are no good words to place with certain things and ear tones are one of those that words don't always match what you are trying to convey."

That's exactly why you should use the Tone Generator -- so that you can tell people what frequency you are hearing. In the case of mixed frequencies, you can use that software to record the sound, and you can send the file to others, so that they could hear your approximation.

�gThis goes back to that silly game of words that has been played here like a broken record. What is sound? Sound is a vibration. So why does one think that this vibration that occurs in earthquake faults cannot be heard? �g

At a great distance? Because of the properties of sound-wave propagation. At a short distance? Because no one else even partially hears sounds (or feels vibrations) that you perceive as huge.

�gIndeed, something does happen in earthquake faults before they move�cThere are steps to the earthquake occurrence.�h

True, �gsomething�h happens, but, again, you are making the mistake of willfully regarding the �grate and state�h idea as somehow bolstering your own idea, without adequately understanding that theory. The theory does not merely say that there is a �gprepartory phase�h but has many specific elements to it. Look again at the article cited by Don:
http://www.xs4all.nl/~carlkop/tidequak.html

�gVidale said that this "preparatory phase" is not well understood and may not be observable until just seconds before an earthquake, if at all. Even if this preparatory phase could be identified in advance, it would not necessarily indicate whether the approaching earthquake will be small, moderate or strong, he cautioned.
Such a "preparatory phase" may be strong enough to negate the lunar tides, and it could explain why the tides play so small a role in triggering earthquakes, Vidale said.�h

This tells us absolutely nothing of use, and in case you thought it might have something to do with overt earthquake precursors, John�fs comments in his {earthquake nucleation} post clearly showed that was not possible:

�gBriefly, the current thinking, although not all agree, is that the sliding in an earthquake starts days aheads of time, starting imperceptibly slowly and accelerating for weeks until it achieves rates comparable with seismic waves - km/s crack speeds and m/s particle velocities.�h

This part sounds encouraging to those who are measuring or sensing precursors. But John continues:

�gTwo problems keep us from finding the "nucleation zone" - (1) it is probably very small, perhaps 1-10 m, (2) the slow precursory slip is tiny, much of the time microns per second or less. Some seismologists don't think such a phase even exists. The theory is called rate-and-state friction, and it has been associated with [.Jim Dieterich].�h

After reading this, it is surprising that anyone would use this theory in support of perceptible or measurable earthquake precursors. It is not surprising that such attempts would meet with skepticism or rejection by John.

I sense a stubborn attitude on both sides of the debate. Maybe that is the �gpreparatory phase�h to understanding each other?

Ara